1. Field of the Invention
The present invention relates to a cassette tape mount for use in a cassette tape recorder in which different types of tape cassettes can be mounted, for example, a tape cassette having a slidable shutter which covers an opening for exposing a magnetic tape, such as a digital compact cassette (hereinafter, referred to as a DCC); and a tape cassette having no shutter wherein a magnetic tape is exposed through an opening, such as an analog compact cassette (hereinafter, referred to as an ACC).
2. Description of the Prior Art
Recently, digital audio equipment has been actively developed for improving reproduction quality. In such a trend, DCCs capable of digital recording and digital reproduction have been a main target for the development. As tape recorders for a DCC, two systems are proposed: R-DAT using a rotary head, and S-DAT using a fixed head. The fixed head of the S-DAT has a similar construction with that of a tape recorder for an ACC which is in general use today. Accordingly, the S-DAT system has an advantage that a DCC which is similar in construction with the ACC can be used. A cassette tape mount which can be used both for a DCC and an ACC has been demanded.
A DCC usually has a shutter on a front face thereof. The shutter is opened by sliding with respect to a cassette main body to expose a stretched portion of a magnetic tape. When the shutter is opened, the stretched portion of the magnetic tape is exposed through openings in the front face of the cassette main body.
An ACC has a cassette main body which holds a magnetic tape with a portion of the magnetic tape in a stretched condition. The cassette main body has uncovered openings in a front face for exposing the magnetic tape, and a portion of the cassette main body in the vicinity of the openings is thicker in a width direction of the magnetic tape than a remaining portion thereof. This portion will be referred to as the thick portion, hereinafter. In the DCC and the ACC, a magnetic head, pinch rollers and the like are inserted into the openings to detect information recorded on the magnetic tape. In this specification, the "front" face of the tape cassette is the side of the DCC and the ACC which is inserted first into the cassette tape mount. The "back" side of the tape cassette is opposite to the front face.
As a cassette tape mount for receiving both of a DCC and an ACC, the one shown in FIG. 11 has been proposed by the applicant of the present invention. In FIG. 11, a cassette tape mount has a shutter operating mechanism 71 for sliding open a shutter of a DCC to uncover openings of the DCC. The shutter operating mechanism 71 includes a pivotable arm 72 which is pressed and thus pivoted by a front face of the DCC which is being inserted. The arm 72 is pivoted while sliding along a guide 80 of a cassette main body. The arm 72 has a shutter operating shaft 77 at an end hereof, and the shutter operating shaft 77 has a contact portion 77a which contacts the shutter of the DCC.
When the DCC is first inserted into the cassette tape mount, the contact portion 77a contacts the cassette main body and slides along the guide 80, and contacts and slides the shutter open with respect to the cassette main body. When the shutter has completely uncovered the openings, the contact portion 77a is put into a lock groove formed in connection with the guide 80, thereby locking the shutter and prohibiting the pivoting of the arm 72 and closing of the shutter.
In order to allow the use of an ACC in a tape mount having the above construction, it is required to prevent the shutter operating mechanism 71 from contacting the exposed magnetic tape when an ACC is inserted. The shutter operating mechanism 71 is controlled so that the contact portion 77a will contact a front face of a thick portion of the ACC and thus the arm is pressed and pivoted by the ACC. When the ACC is completely inserted into the cassette tape mount, the arm 72 is pushed by the front face of the ACC into a fully retracted position.
In the shutter operating mechanism 71 having the above described construction, the contact portion 77a is integrally formed with the shutter operating shaft 77 which is fixed at the end of the arm 72. Accordingly, when a DCC is being inserted, the contact portion 77a does not smoothly slide along the cassette main body or along the shutter. After being recessed in the look groove, the contact portion 77a is not smoothly taken out of the lock groove, thereby possibly causing the contact portion 77a to be pressurized by the shutter. When an ACC is being inserted, the contact portion 77a can come out of engagement from the thick portion, thereby causing the arm 72 to enter the opening and damage the magnetic tape. Such shutter operating mechanisms do not smoothly operate.